<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<style type="text/css">
			*{padding: 0;margin: 0;}
			.wrap{
				width: 512px;
				height: 400px;
				border: 3px solid #808080;
				position: relative;
				overflow: hidden;
				margin: 100px auto;
			}
			.wrap span{
				width: 100%;
				height: 200px;
				position: absolute;		
			}
			.up{
				top: 0;
			}
			.down{
				bottom: 0;
			}
			img{
				position: absolute;
				top: 0;
				left: 0;		
			}
			
			
		</style>
	</head>
	<body>
		<div id="box" class="wrap">
			<img src="images/mi.png"/ id="xiaomi">
			
			<span class="up" id="picUp"></span>
			
			<span class="down" id="picDown"></span>
			
			
		</div>
	</body>
	<script type="text/javascript">
		var up = document.getElementById('picUp');
		var down = document.getElementById('picDown');
		
		var img = document.getElementById('xiaomi')
		
		var count = 0;
		var time = null;
		//鼠标移入的时候吧
		up.onmouseover = function(){
			
			//不管怎样 上来先清定时器
			clearInterval(time);
			time = setInterval(function(){
				count-=3;
				
				count >= -1070 ? img.style.top = count + 'px': clearInterval(time);  
				
				
				
			},30)
		}
		down.onmouseover = function(){
			clearInterval(time)
			
			time = setInterval(function(){
				count+=1;
				
				count < 0 ? img.style.top = count + 'px': clearInterval(time);  
				
				
				
			},30)
		}
		
	
		
	</script>
</html>
